1. Field of the Invention
The present invention relates to an optical disc apparatus that reproduces information recorded on an optical disc having a plurality of information recording layers.
2. Description of the Related Art
Next-generation optical discs such as high definition digital versatile discs (HD DVD) have been emerging which follow digital versatile discs (DVD).
While DVD can have one or two information recording layers, HD DVD can have one to three information recording layers. To write and/or read data to and/or from an optical disc having at least two information recording layers, an optical disc device needs to execute a process of determining on which of the information recording layers laser light concentrated by an objective lens is converging (what is called a layer determination process).
Jpn. Pat. Appln. KOKAI Publication No. 2005-25923 discloses a technique for making determination on the information recording layer with a light receiver placed at a position different from the one where ordinary light receivers are located.
Disadvantageously, owing to the need to install the new light receiver, the invention of Jpn. Pat. Appln. KOKAI Publication No. 2005-25923 complicates the configuration of a light receiving section (what is called a photodetector).